Field
Exemplary embodiments of the present invention relate to a liquid crystal display device.
Discussion of the Background
A liquid crystal display device includes two substrates, on which electric field generating electrodes, such as a pixel electrode and a common electrode, are formed, and a liquid crystal layer interposed between the two substrates. The liquid crystal display device generates an electric field in the liquid crystal layer by applying a voltage to the electric field generating electrode, determines an alignment of liquid crystal molecules of the liquid crystal layer through the generated electric field, and controls polarization of incident light to display an image.
The liquid crystal display device may be categorized as a transmissive liquid crystal display device for displaying an image by using a back light, a reflective liquid crystal display device for displaying an image by using natural external light, and a transflective liquid crystal display device operated in a transmissive type or a reflective type.
Since about 50% of light incident from the back light is absorbed by a polarizing plate attached to a lower part of the liquid crystal display device in a liquid crystal display device using the back light, light efficiency may deteriorate thereby degrading display brightness.
A reflective polarizing plate including first and second layers having different refractive indexes which are repeatedly stacked to allow some light to pass through and allow remaining light to be reflected, thereby improving efficiency of light provided from the backlight, may be used instead of the lower polarizing plate.
Since the first and second layers have different refractive indexes in a reflective polarizing plate, a refractive index in one axis direction among three axes directions may be different. For example, when the first layer is an isotropic thin film and the second layer is a one-axis isotropic thin film, the refractive indexes in the y and z axis directions are the same as each other, but the refractive index in the x-axis direction is different.
Accordingly, it is possible to improve efficiency of light by reflecting light in the x-axis direction incident from the back light and allowing light in the y-axis direction to pass through.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the inventive concept, and, therefore, it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.